Polypropylene film drying was a manufacturing headache for at least one company because operators frequently had to scrape buildup off the nozzles. Advance Systems Inc., Green Bay, Wis., retrofitted the plant’s existing dryer with its Smooth Float air foil unit. Here’s how the retrofit made the difference.

The customer ran only polypropylene film with a range of thicknesses that approached 200 micron on the high end, and wet adhesive coating weights that could exceed 100 gsm (61 lb per ream). The weight of the products meant that they likely would be somewhat harder to process than paper when it came to stability and tensile strength.

The film manufacturer told Advance Systems that personnel were almost constantly scraping the nozzles to remove buildup of the release coat, which was not doing its job. The release materials got so hard and rigid that they began to damage the web, resulting in the scheduling of a full maintenance shift at least every two weeks.

Then Advance Systems retrofitted the dryer with its Smooth Float air foil unit. Now, more than a year after the retrofit, the nozzles only require a monthly half-shift for maintenance to remove a small amount of buildup at the edges of the web. The customer says there is no quality issue with its products.

According to the customer, it is easy and quick to clean the Smooth Float’s bottom nozzles. Cleaning the top nozzles on the adhesive side is “more elaborate,” but they only get dirty if the web breaks, the customer says, noting that the quick-locking system makes it easier than in the past to remove the top nozzles for cleaning.

“With the new nozzles, we could increase the machine speed, depending on the product, at least 10 percent, and lower the tensions in the dryer as well, about 50 percent,” the customer reports. “Our system includes an inert dryer and condensation system, and an atmospheric dryer after that, with an RTO [regenerative thermal oxidizer]. Due to the faster drying, we could recover about 10 percent more solvents with our recovery system.”

For more information on Advance Systems dryers, go to www.advancesystems.com.